1. Field of the Invention
This invention relates to the control of organisms, such as microorganisms, and in particular the inhibition of such organisms by employing hop acids to inhibit the growth of such organisms and/or kill such organisms. By way of illustration only, the invention has particular utility in aqueous systems, such as papermaking systems and process water systems, in particular systems that involve circulating and/or recirculating water systems, such as cooling water systems, etc.
2. Background of the Invention and Related Art
The control of organisms, and microorganisms in particular, has been a continuing and troublesome problem in aqueous systems, such as systems that involve circulating and/or recirculating water systems, such as such as papermaking systems and process water systems, cooling water systems, etc. Such microorganisms cause biofouling, such as deposits of microorganisms or products (such as metabolic products) of microorganisms that cause the formation of deposits such as films, mats and other deposits which can result in plugging of pores, reduced flow, reduced heat exchange rates, clogging, etc.
Slime formation, deposit formation and the formation of filamentous bacteria have been of particular concern, for example.
By way of non-limiting example only, filamentous bacteria (for example, Sphaerotilus natans) are often the cause of deposits on paper machines and fouling in cooling systems. Many types of filamentous bacteria grow on submerged surfaces in single chains within structures referred to as xe2x80x9csheaths.xe2x80x9d Sheaths are considered to be a protective structure, and as such, the structure promotes the survival of the organism. For example, the sheath structure is thought to protect the organism from biocides, because, for example, getting the biocide into the protective structure poses a problem. Filamentous bacterial growth on submerged surfaces in paper process streams can contribute to the formation of large deposits consisting of cells and inert materials (particulates, fines, fiber, etc.) that become enmeshed in the filaments. Long xe2x80x9cstringersxe2x80x9d of the filamentous bacteria as well as large clumps of deposits can become dislodged and cause problems such as holes, other defects, and breaks in the paper. This, therefore, can cause significant increases in the cost of producing paper. Filamentous bacteria also cause problems in cooling towers. Submerged surfaces fouled with filamentous and other types of bacteria cause a reduction in the efficiency of heat transfer, in cooling systems for example, as well as other problems resulting from large amounts of biomass becoming dislodged and circulating within an industrial setting.
The control of such microorganisms is even more difficult in view of the fact that many of the microorganisms which are the cause of such problems are resistant to attempts to control them, such as by inhibiting their growth and/or killing them. For example, microorgansims that pose problems in aqueous industrial systems, such as process waters and papermaking systems, are resistant to a broad spectrum of conditions and materials, and thus are able to remain viable in a wide variety of such conditions. Therefore, biocides have been employed in efforts to control such microorganisms. However, conventional biocides are expensive, are not sufficiently environmentally friendly, exhibit an undesirably broad spectrum of activity (i.e., they are not targeted to the specific microorganisms desired to be killed), must be employed in relatively large concentrations, and/or can be harmful and/or dangerous and/or even toxic to humans. Moreover, in aqueous systems or media in which the control of organisms is desired, the compatibility of the compositions and methods employed are also a consideration. Accordingly, a biocide which is effective with regard to the foregoing and which does not exhibit the mentioned disadvantages is desired.
With respect to all of the foregoing, there has been a continuing need for improvement.
It is known in the brewing industry that some hop acids can inhibit the growth of microorganisms that can cause spoilage in beer. For example, U.S. Pat. No. 5,082,975 discloses that the hop acid, hexahydrolupulone, can inhibit the growth of certain Lactobacillus. This patent further discloses that there has been speculation that hops may have helped control brew house bacterial infections due to the presence of hop acids in the wort and beer. However, since the hop beta acids are not found in beer, such control, if it indeed existed, was thought to have been due to the hop alpha acids and iso-alpha acids. Beta acids are known to be highly unstable, being oxidized in the boiling wort to bitter hulupones and by themselves to deteriorate in a matter of days or hours after crystallization. This lack of stability is now shown to be overcome by conversion to hexahydrolupulone (hexahydro beta acids). There is a vast excess of lupulone available as a result of being discarded in the brewing process, making it a potentially inexpensive raw material. U.S. Pat. No. 4,918,240 is a related patent to U.S. Pat. No. 5,082,975. Each of these patents is hereby incorporated by reference as though set forth in full herein.
U.S. Pat. No. 5,455,038 discloses that the hop acids, tetrahydroisohummulone and hexahydrocolupulone (xcex1 and xcex2 hops, respectively), a product of the brewing industry, have been identified as compounds that can inhibit food born pathogens from the genera Listeria, Staphylococcus, Bacillus, and Clostridium. In addition, U.S. Pat. No. 5,286,506 discloses that solid food products can be protected from food pathogens, including Listeria monocytogenes, by incorporating beta-acids, which are extracted from hops, into such food products. U.S. Pat. No. 5,455,038 discloses the inhibition of Listeria with xcex1 and xcex2 hop acids. Each of these patents is hereby incorporated by reference as though set forth in full herein.
Derivatives of the xcex2-hydrogenated lupulones can inhibit or kill cancer cells (WO 97/31630 and WO 98/11883) as well as antibiotic resistant strains of Staphylococcus aureus, Mycobacterium tuberculosis, and Mycobacterium avian Complex or enterococcus (xe2x80x9cAntimicrobial activity of the Semisynthetic Compound, Hexahydrocolupolonexe2x80x9d, Stephan et al., Journal of Antimicrobial Chemotherapy (1998) 41, 519-522). Each of these documents is hereby incorporated by reference as though set forth in full herein. Additionally, xcex1 and xcex2 hop acids have been identified as a therapeutic agent for methicillin resistant Staphylococcus aureus (Japanese Patent document JP 9067250). This document is hereby incorporated by reference as though set forth in full herein.
U.S. Pat. No. 5,370,863 discloses that oral care compositions containing hop acids or their salts are effective in inhibiting Gram positive bacteria, including Streptococcus mutans, which can cause plaque or periodontal disease, which document is hereby incorporated by reference as though set forth in full herein. A representative composition is a toothpaste containing tetrahydroisohumulone.
Hop acids have been considered to be selective to Gram-positive bacteria. See, for example, WO 98/11883, incorporated by reference above.
The invention provides a method of controlling organisms, such as microorganisms, particularly bacteria, in aqueous systems or media, such as papermaking systems and process water systems, in particular systems that involve circulating and/or recirculating water systems, such as cooling water systems, etc., which method employs materials which are readily available from renewable resources and which are also effective.
The invention provides a method of controlling such organisms in such aqueous systems which method employs materials which are relatively inexpensive.
The invention provides a method of controlling such organisms in such aqueous systems which method is effective against a wide variety of microorganisms but which are also targeted to the microorganisms which affect such aqueous systems.
The invention provides a method of inhibiting the growth of organisms in an aqueous system selected from a papermaking system, a cooling system or a process water which process water does not contact a final product; or combinations thereof, comprising adding to the aqueous system a hop acid.
Preferably, the hop acid comprises a member selected from xcex1 or xcex2 hop acids, and mixtures thereof.
In preferred embodiments, the method comprises adding a hop acid selected from one or more of a compound of Formula (I): 
wherein xe2x80x9c----xe2x80x9d represents an optional double bond;
R1 comprises a member selected from OH; and saturated, or unsaturated (containing from about 1 to about 5 double bonds), straight- or branched-chain alkyl or alkenyl of from about 1 to about 20 C atoms, more preferably from about 1 to about 10 C atoms and more preferably from about 1 to about 5 C atoms;
R2 comprises a member selected from xe2x80x94OH; xe2x95x90O; xe2x80x94SH; xe2x95x90S; and saturated, or unsaturated (containing from about 1 to about 5 double bonds), straight- or branched-chain alkyl or alkenyl of from about 1 to about 20 C atoms, more preferably from about 1 to about 10 C atoms and more preferably from about 1 to about 5 C atoms;
R3 comprises a member selected from xe2x80x94OH; xe2x95x90O; xe2x80x94SH and xe2x95x90S; and xe2x80x94OOR, wherein R comprises a member selected from H and CnH2nxe2x88x921, where n is an integer of from about 2 to about 10, more preferably from about 2 to about 7, and more preferably from about 2 to about 5;
R4 comprises a member selected from saturated or unsaturated (containing from about 1 to about 5 double bonds), straight- or branched-chain alkyl or alkenyl of from about 1 to about 20 C atoms, more preferably from about 1 to about 10 C atoms, and more preferably from about 1 to about 5 C atoms; a ketone of from about 1 to about 20 carbon atoms, more preferably from about 1 to about 10 carbon atoms, and more preferably from about 1 to about 4 carbon atoms, an aldehyde of the general formula C(O)H, or a ketone of the general formula C(O)CnH2n+1, where n is an integer of from about 2 to about 10, more preferably from about 2 to about 7, and more preferably from about 2 to about 5; and xe2x80x94OOR, wherein R comprises a member selected from CnH2n+1 wherein n is as defined previously, and H; and/or Formula (II): 
wherein R5 comprises a ketone of the general formula C(O)CnH2nxe2x88x921, where n is an integer of from about 2 to about 10, more preferably from about 2 to about 7, and more preferably from about 2 to about 5;
R6 comprises a member selected from xe2x80x94OH, xe2x80x94SH, and xe2x80x94OOR, wherein R comprises a member selected from CnH2n+1 where n is an integer of from about 2 to about 10, more preferably from about 2 to about 7, and more preferably from about 2 to about 5; and H; and
R7 comprises a member selected from saturated or unsaturated (containing from about 1 to about 5 double bonds), straight- or branched-chain alkyl or alkenyl of from about 1 to about 20 C atoms, more preferably from about 1 to about 10 C atoms, and more preferably from about 1 to about 5 C atoms;
R8 comprises member selected from saturated or unsaturated (containing from about 1 to about 5 double bonds), straight- or branched-chain alkyl or alkenyl of from about 1 to about 20 C atoms, more preferably from about 1 to about 10 C atoms, and more preferably from about 1 to about 5 C atoms; a ketone of from about 1 to about 20 carbon atoms, more preferably from about 1 to about 10 carbon atoms, and more preferably from about 1 to about 4 carbon atoms, an aldehyde of the general formula C(O)H, or a ketone of the general formula C(O)CnH2n+1, where n is an integer of from about 2 to about 10, more preferably from about 2 to about 7, and more preferably about 5; and/or Formula (III): 
wherein R9 comprises a saturated, or unsaturated (containing from about 1 to about 5 double bonds), straight- or branched-chain alkyl or alkenyl of from about 1 to about 20 C atoms, more preferably from about 1 to about 10 C atoms and more preferably from about 1 to about 5 C atoms; and
R10 comprises a member selected from a ketone of from about 1 to about 20 carbon atoms, more preferably from about 1 to about 10 carbon atoms, and more preferably from about 1 to about 4 carbon atoms, an aldehyde of the general formula C(O)H or a ketone of the general formula C(O)CnH2nxe2x88x921, where n is an integer of from about 2 to about 10, more preferably from about 2 to about 7, and more preferably from about 2 to about 5; and/or Formula (IV): 
wherein R11 comprises a saturated, or unsaturated (containing from about 1 to about 5 double bonds), straight- or branched-chain alkyl or alkenyl of from about 1 to about 20 C atoms, more preferably from about 1 to about 10 C atoms and more preferably from about 1 to about 5 C atoms; and
R12 comprises a member selected from a ketone of from about 1 to about 20 carbon atoms, more preferably from about 1 to about 10 carbon atoms, and more preferably from about 1 to about 4 carbon atoms, an aldehyde of the general formula C(O)H, or a ketone of the C(O)CnH2nxe2x88x921, where n is an integer of from about 2 to about 10, more preferably from about 2 to about 7, and more preferably from about 2 to about 5.
Preferably R4 comprises a substituent of the formula 
wherein R13 comprises a C3-C8 alkyl group.
Preferably R13 comprises a member selected from xe2x80x94CH2CH(CH3)2; xe2x80x94CH(CH3)2; and xe2x80x94CH(CH3)2CH2CH3.
Preferably the method comprises adding a hop acid which comprises a member selected from hexahydrolupulone; hexahydrocolupulone; hexahydroadlupulone, and mixtures thereof.
Preferably the hop acid comprises hexahydrocolupulone.
Preferably R8 comprises a substituent of the formula 
wherein R14 comprises a C3-C8 alkyl group.
Preferably R14 comprises a member selected from CH2CH(CH3)2; xe2x80x94CH(CH3)2; xe2x80x94(CH2)2CH(CH3)2; xe2x80x94CH(CH3)2 CH2CH3. and mixtures thereof.
Preferably the hop acid comprises tetrahydroisohumulone.
The organism can comprise a microorganism selected from Gram-negative bacteria, Gram-positive bacteria, and mixtures thereof.
The microorganism can comprise a member selected from Sphaerotilus natans, Clostridium butyricum, Pseudomonas aeruginosa, Curtobacterium flaccumfaciens, Burkholderia cepacia, Pseudomonas glathi, Bacillus cereus, Bacillus maroccanus, Bacillus licheniformis, Bacillus sphaericus, Bacillus subtilis, and mixtures thereof.
The microorganism can comprise a Gram-negative bacteria.
The microorganism can comprise a member selected from Altermonas, Aquaspirillum, Campylobacter, Helicobacter, Acinetobacter, Agrobacterium, Alcaligenes, Alteromonas, Flavobacterium, Pseudomonas, Xanthomonas, Mycoplasma, Methanococcus mixtures thereof.
The microorganism can comprise a Gram-positive bacteria.
The microorganism can comprise a member selected from Bacillus, Enterococcus, Planococcus, Staphylococcus, Streptococcus, Clostridium, Lactobacillus, Listeria, Actinomyces, Arthrobacter, Corynebacterium, Curtobacterium, Norcardia, Actinoplanes, Mycobacterium and mixtures thereof. mixtures thereof.
The aqueous system can comprise a papermaking system.
The aqueous system can comprise a process water.
The aqueous system can comprise a cooling system.
The hop acid preferably is present in an amount of from about 0.001 to about 1,000 ppm.
The hop acid is preferably present in an amount of from about 0.1 to about 250 ppm.
The hop acid is preferably present in an amount of from about 0.1 to about 100 ppm.
The hop acid is preferably added with a freezing point depressant.
The invention also comprises a method of inhibiting the growth of organisms in a papermaking system, comprising adding to the papermaking system a hop acid in accordance with any of the foregoing definitions.
The invention also provides a composition comprising a hop acid in accordance with any of the foregoing definitions and a member selected from a papermaking suspension, a defoamer, an alum, an adhesive, a paper mill coating, a pigment slurry, a starch, a pitch control agent, a scale control agent, a sizing agent, and mixtures thereof.
Preferably, the papermaking suspension comprises a member selected from refined or unrefined furnish stock; refined or unrefined pulp; paper making furnish, and combinations thereof.
The invention also provides a cellulosic product comprising a member selected from paper and paper board.
The paper can comprise a member selected from stationery paper, paper towel and tissue paper.